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Patellofemoral evaluation with magnetic resonance imaging in 51 knees of asymptomatic subjects.

Nicolaas L, Tigchelaar S, Koëter S - Knee Surg Sports Traumatol Arthrosc (2011)

Bottom Line: Patients with patella alta and significant hydrops were excluded.The results represent patellofemoral values in the normal population.Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

ABSTRACT

Purpose: The objective of this study is to evaluate patellofemoral joint imaging on magnetic resonance imaging (MRI) in asymptomatic subjects to assess normal values and to test statistical correlation and reliability of MRI scan.

Methods: An analysis of 51 standard MRI examinations was performed. Sulcus angle (SA), patellar axis (PA), lateral patellofemoral angle (LPFA), and lateral patellofemoral length (LPL) were measured. None of the patients suffered from patellofemoral complaints. Patients with patella alta and significant hydrops were excluded. The measurements were assessed with a 2-week interval by two raters under blinded conditions. Statistical analysis was applied by an independent analyst.

Results: The mean SA referenced 142.4 ± 6.9°, PA 5.3 ± 3.8°, LPFA 13 ± 4.4°, and LPL 0.8 ± 2.9 mm. Inter-observer variability showed high correlation for LPL and PA, as the repeatability coefficient was high (LPL; 1.49 (LN), 5.7 (ST) and PA; 4.1 (LN), 5.8 (ST). Also, intra-observer variability showed good correlation for LPL and PA.

Conclusion: The results represent patellofemoral values in the normal population. They indicate that MRI is a reliable imaging technique to determine lateral patellofemoral length and patellar axis. Lateral patellofemoral angle and sulcus angle showed a poor correlation and should not be used for decision making.

Level of evidence: Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

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Related in: MedlinePlus

Sulcus angle
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Fig1: Sulcus angle

Mentions: Measurements on axial MR images included the following parameters: The sulcus angle (SA) was measured using the chondral outline of the trochlea with the axial section at the level of the Roman arch (Fig. 1). Also at this level, we measured the patellar axis (PA) as described by Dejour et al. [6], which is the angle between the midline axial section of the patella and the line drawn parallel to the posterior femoral condyles (Fig. 2). The lateral patellofemoral length (LPL) is the distance between the most lateral part of the patella and the line drawn parallel to the lateral side of the femur condyl (Fig. 3). Lateral patellofemoral angle (LPFA), as described by Laurin et al. [10], is the angle between the line parallel to the tip of the anterior condyles and the lateral patellar facet (Fig. 4). Values were measured in degrees (SA, PA, and LPFA) and millimeters (LPL) up to one-decimal accuracy.Fig. 1


Patellofemoral evaluation with magnetic resonance imaging in 51 knees of asymptomatic subjects.

Nicolaas L, Tigchelaar S, Koëter S - Knee Surg Sports Traumatol Arthrosc (2011)

Sulcus angle
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3176398&req=5

Fig1: Sulcus angle
Mentions: Measurements on axial MR images included the following parameters: The sulcus angle (SA) was measured using the chondral outline of the trochlea with the axial section at the level of the Roman arch (Fig. 1). Also at this level, we measured the patellar axis (PA) as described by Dejour et al. [6], which is the angle between the midline axial section of the patella and the line drawn parallel to the posterior femoral condyles (Fig. 2). The lateral patellofemoral length (LPL) is the distance between the most lateral part of the patella and the line drawn parallel to the lateral side of the femur condyl (Fig. 3). Lateral patellofemoral angle (LPFA), as described by Laurin et al. [10], is the angle between the line parallel to the tip of the anterior condyles and the lateral patellar facet (Fig. 4). Values were measured in degrees (SA, PA, and LPFA) and millimeters (LPL) up to one-decimal accuracy.Fig. 1

Bottom Line: Patients with patella alta and significant hydrops were excluded.The results represent patellofemoral values in the normal population.Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

ABSTRACT

Purpose: The objective of this study is to evaluate patellofemoral joint imaging on magnetic resonance imaging (MRI) in asymptomatic subjects to assess normal values and to test statistical correlation and reliability of MRI scan.

Methods: An analysis of 51 standard MRI examinations was performed. Sulcus angle (SA), patellar axis (PA), lateral patellofemoral angle (LPFA), and lateral patellofemoral length (LPL) were measured. None of the patients suffered from patellofemoral complaints. Patients with patella alta and significant hydrops were excluded. The measurements were assessed with a 2-week interval by two raters under blinded conditions. Statistical analysis was applied by an independent analyst.

Results: The mean SA referenced 142.4 ± 6.9°, PA 5.3 ± 3.8°, LPFA 13 ± 4.4°, and LPL 0.8 ± 2.9 mm. Inter-observer variability showed high correlation for LPL and PA, as the repeatability coefficient was high (LPL; 1.49 (LN), 5.7 (ST) and PA; 4.1 (LN), 5.8 (ST). Also, intra-observer variability showed good correlation for LPL and PA.

Conclusion: The results represent patellofemoral values in the normal population. They indicate that MRI is a reliable imaging technique to determine lateral patellofemoral length and patellar axis. Lateral patellofemoral angle and sulcus angle showed a poor correlation and should not be used for decision making.

Level of evidence: Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Show MeSH
Related in: MedlinePlus